Sometimes you don't have enough time, you're too tired, or you're just plain running low on libido. On average, Americans have sex 1.2 times a week. But it's also not uncommon for couples to have sex less than once a month.

While most couples wish they were having sex more often, you might be surprised by how many benefits there are for having more sex. According to scientific research, having sex with your spouse more often can do wonders for both your relationship and your health.

Here are eight reasons you should be having sex with your spouse as much as possible.

1. To look younger

People who have sex frequently are perceived as 7-12 years younger than they actually are. In a study conducted at the Royal Edinburgh Hospital, a group of people guessed participants' ages through a one-way mirror. The participants who had sex at least four times a week were perceived roughly a decade younger than their actual age.

Interestingly, these results did not hold true for participants who have casual sex with multiple partners or for participants who were cheating on their partner. Clinical neuropsychologist David Weeks concluded that sex only makes you look younger if you are doing it in a relationship where there is empathy and compatibility.

2. To keep you committed

It turns out that men who have sex with their spouse more often are less likely to cheat than those who rarely have sex with their spouse.

A scientific explanation for this is that oxytocin — a hormone that promotes bonding — is released in large amounts during sex; so those who have sex more often are more powerfully attached to their partners.

In one experiment, researchers sprayed men with oxytocin or a placebo and then had an attractive woman stand at different distances while the men rated their comfort levels. Men in monogamous relationships that had been sprayed with oxytocin preferred to keep a greater distance from the "temptress" than those sprayed with the placebo. The researchers concluded that oxytocin promotes bonding with your significant other instead of strangers.

3. To sleep better

During sex your body decreases in levels of cortisol, a stress hormone. This leaves you feeling relaxed and therefore more prepared to have a good night's sleep. Not only that, but sex increases estrogen levels in women, which is powerful in enhancing deep sleep and REM cycles.

4. To lose weight

It shouldn't come as a surprise that sex is a great physical activity and can help you lose weight. Not only can it be more fun than hitting the gym, but it burns a good amount of calories.

5. To ward off colds

People who have frequent sex take less sick days, get fewer colds, and have an overall stronger immune system. This is because people who have sex more often have higher levels of IgA — antibodies that fight viruses, toxins and bacteria.

This is particularly true in women. Women's bodies react to sex by preparing for conception. Part of this preparation is warding off any possible infections.

6. To be less depressed

It's probably not surprising that people who have sex frequently are happier than those who don't. But the jury's still out about whether depressed people are less likely to have sex because they're depressed or whether they're depressed because they aren't having sex.

On the other hand, one thing researchers are pretty positive about is that semen has mood-boosting compounds. This means that sex can be particularly effective in warding off depression for women.

8. To lower blood pressure

Studies show that sexual intercourse has the power to lower blood pressure. Believe it or not, research also reveals that other sexual activities, such as masturbation and looking at pornography, don't have the same positive impact on cardiovascular health.